We use the conformable \(\alpha \) -fractional derivative, recently introduced in [1]}, [2]}, which for \(\alpha \in (0,1]\)  is given by
\(D_{*}f(t):=\lim _{\varepsilon \rightarrow 0}\frac{f(t+\varepsilon t^{1-*})-f(t)}{\varepsilon }, \quad D_{*}f(0)=\lim _{t\rightarrow 0^+}D_{*}f(t).\) 
